So, basically, I have been doing some sound tests last night, and trying to figure out, or come to a conclusion about which DAC I want to use. I hope you can help me out. My current setup is a Cambridge Audio CXA80 with Monitor Audio Silver 100. Originally, I had the streamer fed into a pair of powered speakers by a digital coaxial cable. I have now connected it to my Cambridge Audio CXA80 amp via Digital Coaxial, but also Analogue RCA cables. What I have found out that the Analogue signal sounds so much clear, fuller(louder?), musical, and agile compared to the digital signal which sounded too mellow and compressed? (have to adjust volume slightly louder). My question is: If I’m using the analogue input on my amp, am I bypassing the Cambridge DAC(Wolfson 8740) and using the Arylic DAC instead? And obviously if I have a digital connection from the streamer to the amp, I’m using the Cambridge DAC?
Hi, I don’t know how the Cambridge Audio CXA80 designed, so I’m not sure whether the analog output of S50PRO+ is going through an extra AD-DA conversion inside the AMP. Since you can notice the audio difference, you can choose the better one 
Regarding the volume, S50PRO+ is designed to have max 2Vrms for the analog output, which means when you play a 0dB sine wave test file, the voltage of analog output will reach 2Vrms when set to max volume. And the final volume of sound into your ear depends on how AMP handles the analog input levels, it will cause the volume difference you’ve noticed.
Can i connect Rotel RB 990bx poweramp with an Input sensitivity: 1V…will it work fine??
You could, but better not increase the volume of S50 exceed 80%, or else will have clipping.
Thanks for the suggestion